Inductive Position Sensor Using Goertzel Filter for Signal Demodulation

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Solution Overview

Problem

Existing position sensors require complex signal regeneration to detect the position of movable objects, which can be inefficient and prone to errors.

Innovation Solution

A position sensor system utilizing a frequency generator, multiple electrical signal sources, secondary coils, and a Goertzel filter bank for efficient demodulation of signals, eliminating the need for complex signal regeneration and allowing for precise position detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex signal regeneration is used to detect position, then measurement precision can be maintained, but device complexity increases significantly

Engineering Contradiction:
Improveposition detection accuracyVSAvoidsignal regeneration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex signal regeneration stage from the traditional position detection system. Instead of regenerating the carrier signal through complex circuits, the invention directly processes the induced secondary coil signals through frequency conversion and Goertzel filtering to extract position information, thereby removing the problematic complex regeneration component while maintaining measurement precision.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the traditional analog signal regeneration mechanism with a digital signal processing approach. By using a frequency converter and Goertzel filter bank implemented in digital domain, the system achieves accurate position detection without requiring complex analog signal regeneration circuits, thus substituting a simpler digital system for the complex mechanical/analog system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If traditional frequency conversion methods are used, then signal processing is possible, but processing time increases

Engineering Contradiction:
Improvesignal demodulation accuracyVSAvoidsignal processing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary frequency conversion to transform the secondary coil signals into a standardized intermediate frequency range before demodulation. This preliminary action prepares the signals in advance for efficient Goertzel filtering, enabling faster and more accurate extraction of position information without requiring time-consuming iterative processing during the measurement phase.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the frequency parameter of the signals through frequency conversion, transforming them from their original carrier frequencies into an intermediate frequency range optimized for Goertzel filtering. This parameter transformation enables more efficient signal processing and faster position calculation compared to traditional methods that operate directly at the original carrier frequencies.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system enables efficient and accurate detection of the position of movable objects without complex signal regeneration, improving accuracy and simplifying assembly and processing.

Implementation Method 1

a primary coil (101) for generating an alternating magnetic field with the first frequency; a first secondary coil (103) and a second secondary coil (105), wherein the first secondary coil and the second secondary coil can each be magnetically coupled to the primary coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a frequency converter for converting the third electrical signal to a first intermediate frequency signal and for converting the fourth electrical signal to a second intermediate frequency signal

Methodology Applied
Scientific EffectFrequency conversion:

Implementation Method 3

a Goertzel filter bank for demodulating the first intermediate frequency signal to obtain a first demodulated signal and for demodulating the second intermediate frequency signal to obtain a second demodulated signal

Methodology Applied
Scientific EffectSignal demodulation:

Data Source

PatentEP3198234B1Inductive position sensor with frequency converter and goertzel filter for analyzing signals
Publication Date: 2020.04.29 CONTINENTAL TEVES AG & CO OHG
  • EP3198234B1 patent drawingFigure 1
  • EP3198234B1 patent drawingFigure 2
  • EP3198234B1 patent drawingFigure 3

AI summary

The invention relates to a position sensor (100) for detecting a position of a position transmitter. The position sensor (100) can be connected to a first electric signal source in order to output a first electric signal with a first frequency and to a second electric signal source in order to output a second electric signal with a second frequency. The position sensor comprises the following: a primary coil (101) for generating a magnetic alternating field with the first frequency; a first secondary coil (103) and a second secondary coil (105), wherein the first secondary coil (103) and the second secondary coil (105) can each be magnetically coupled to the primary coil (101) by means of the position transmitter, and a third electric signal can be induced in the first secondary coil (103) and a fourth electric signal can be induced in the second secondary coil (105) by the generated magnetic alternating field; a frequency converter (107) for converting the third electric signal into a first intermediate frequency signal and for converting the fourth electric signal into a second intermediate frequency signal, said frequency converter (107) being connectable to the second electric signal source; and a Goertzel filter bank (109) for demodulating the first intermediate frequency signal in order to obtain a first demodulated signal and for demodulating the second intermediate frequency signal in order to obtain a second demodulated signal.